A secure mechanical engagement is necessary to achieve a good electrical connection between a lead of an electrical component and a corresponding socket. In many connectors, the lead and the electrical contacts of the socket are biased against one another when the lead is fully seated in the socket. Thus as the lead is being inserted in or removed from the socket the biasing force must be overcome.
Although the above described electrical connectors are acceptable for many applications, there are other applications where the biasing force encountered as the lead is inserted into the socket may damage the lead or an electrical component connected to the lead. Specifically, many dual-in-line integrated circuit (IC) packages, computer chips having leads extending from four sides or small transistors with concentrically arranged leads are sufficiently fragile to create a possibility of damage as the leads are inserted in or removed from a socket. Damage is particularly likely to occur if an IC package, for example, is twisted even slightly to overcome the biasing force during removal of the IC package from the socket.
IC packages and other such components frequently are used with zero insertion force connectors to avoid any damage that might be incurred as the IC package is inserted in or removed from a socket. Zero insertion force connectors are generally constructed with movable electrical contacts. More particularly the contacts on the zero insertion force connector can be moved into a position where they will not touch the leads of the IC package. As a result, the IC package can be placed in or removed from the zero insertion force connector without encountering the biasing forces of the contacts in the connector. However, once the IC package is in position the electrical contacts of the zero insertion force connector can be moved into mechanical and electrical engagement with the leads.
A variety of zero insertion force connectors have been developed for use with dual-in-line integrated circuit packages. Typically, the known zero insertion force connector comprises a base member into which a plurality of electrical contacts are placed, a cover member which at least partially covers and retains the electrical contacts, and one or more cam members which are movable between the cover and base to force the individual electrical connectors into contact with the pins of the IC package.
One specific zero insertion force connector is shown in U.S. Pat. No. 4,080,032 which issued to Cherian et al. The connector shown in U.S. Pat. No. 4,080,032 includes a base, a cover, a draw bar and a pair of chanel shaped actuator members. The draw bar and actuator members each contain a plurality of cooperating ramps and slots. A longitudinal movement of the draw bar shown in the device of U.S. Pat. No. 4,080,032 is translated into a lateral movement of the actuator members by virtue of the cooperation between the ramps on the respective members. This lateral movement of the actuator members, in turn, causes the electrical contacts to be open or closed.
Another zero insertion force connector is shown in U.S. Pat. No. 4,314,736 which issued to Demnianiuk. The connector shown in U.S. Pat. No. 4,314,736 also includes a base and a cover, and achieves a camming action through cooperation of a rotating lever, camming arms and engaging arms. More particularly rotation of the lever in the connector of U.S. Pat. No. 4,314,736 is translated into a lateral movement of the engaging bars which, in turn, moves the electrical contacts toward or away from the individual pins.
Still another type of zero insertion force connector is disclosed in U.S. Pat. No. 3,891,289 which issued to Hanke. The connector shown in U.S. Pat. No. 3,891,289 uses a centrally located, generally eliptically configured cam which is rotatable about an axis which extends generally perpendicular to the contact. Rotation of this eliptical cam can urge the connectors into contact with the pins. U.S. Pat. No. 3,568,134 which issued to Anhalt et al shows a connector similar to the one described in U.S. Pat. No. 3,891,289.
Finally another known connector has a housing into which a plurality of contacts are loosely placed. Each contact includes a pair of generally parallel arms which are spaced apart such that the pin of an IC package can be inserted therebetween. An actuator is telescopingly mounted on the housing and connected to the housing by four jack screws. In use the pins of the IC package are loosely positioned between the arms of the respective contacts. The jacks screws then are rotated to draw the actuator toward the housing in a direction generally parallel to the pins and the contact arms. This movement causes the actuator to press down on one arm of each contact, causing that arm to bend toward and touch the pin. This structure would be costly to manufacture and difficult to operate because of the screws. Additionally the ability of the loosely mounted contacts to move freely makes proper mounting of the IC package difficult, and can result in damaged pins. Furthermore the actuator tends to cause the arms to lose their resiliency so that they may remain in a closed position or may not adequately contact the pin.
Although some of the above described zero insertion force connectors have generally satisfactory electrical performance, they are relatively expensive to make, difficult to assemble, and cumbersome to operate. More particularly the requirement of a relatively great number of cooperating parts substantially contributes to manufacturing costs and assembly time. Additionally, since the IC packages with which the prior art connectors typically are used are quite small, the connectors and the cams mounted therein are comparably small. This small size makes manipulation of the small cam member difficult to accomplish.
Accordingly it is an object of the subject invention to provide a zero insertion force connector which has few moving parts and is not likely to damage electrical contacts or pins.
It is an additional object of the subject invention to provide a zero insertion force connector which can be operated without special tools.
It is a further object of the subject invention to provide a zero insertion force connector which will securely retain electrical contacts.
It is still an additional object of the subject invention to provide a zero insertion force connector which can be manufactured, assembled, and operated easily and at a low cost.